MAP65: A Panoramic, Polarization-Matching Receiver for JT65

摘要

MAP65 is a computer program designed as the back end of a wideband polarization-matching receiver for JT65 signals. It works together with the Linrad software written by SM5BSZ, and ideally takes advantage of RF and IF hardware providing signal channels for two orthogonal polarizations. As an example, my current 144 MHz station uses dual-polarization yagis and matched baseband converters. Linrad uses a four-channel 24-bit soundcard to sample I and Q baseband signals for each polarization at 96 kHz. After Linrad's superb wideband noise blanking has been applied, the digitized signals are passed on to MAP65. MAP65 automatically finds all detectable JT65 signals in a 90 kHz passband, matches the linear polarization angle of each one, decodes their messages, and provides the operator with a "band map" displaying callsigns, operating frequencies, polarization angles, and messages received over the past 20 minutes or so. MAP65 provides a companion transmitting facility, and it runs under either Windows or Linux. Its principal intended application is EME or "moonbounce" on the amateur VHF and UHF bands. Many of its features will also be useful on the microwave bands, for both EME and terrestrial contacts.